Preheat the oven: Preheat the oven to 400°F.
Make the seasoning: In a small bowl, mix together all the taco seasoning ingredients until well combined. Set aside.
Cook the beef: Heat a large sauté pan over medium heat. Add the ground beef and finely chopped onion, breaking up the beef into small pieces with a wooden spoon. Cook for 5 to 7 minutes, until the beef is mostly browned but still slightly red in some spots.
Drain the grease: Drain off all but 1 to 2 tablespoons of the accumulated juices. Push the cooked beef to one side of the pan, tilt the pan slightly, and use a dry paper towel to soak up the excess grease.
Add garlic and seasoning: Stir in the minced garlic, chopped cilantro stems, and prepared taco seasoning. Cook for another minute, stirring to coat the beef.
Add tomato paste: Make a well in the center of the pan and add the tomato paste. Let it cook for about a minute, then stir it into the beef.
Finish the filling: Continue cooking until the beef is fully cooked and no pink remains. In the last 2 minutes of cooking, stir in the refried beans until fully incorporated. Remove from heat and set aside.
Prep the tortillas: Line a large baking sheet with parchment paper. Place the tortillas on the sheet and lightly brush both sides with olive oil using a silicone basting brush.
Assemble the tacos: Spoon about ⅓ cup of the beef mixture using a slotted spoon to avoid transferring excess oil onto one half of each tortilla. Continue filling the tortillas until you run out of meat, which usually makes about 8 tacos. Top with grated cheese, fold the tortilla in half, and sprinkle a bit more cheese on top.
Bake: Bake for about 15 minutes, or until the tortillas are golden and the cheese is bubbly.
Make avocado lime crema: In a food processor, add the avocados, freshly squeezed lime juice, sour cream, salt, and torn cilantro.
Blend until smooth: Process until the mixture is creamy and fully blended, scraping down the sides as needed. Give it a quick taste. Add a little more lime juice or salt if needed to balance the flavors to your liking.
Serve: Dress the crispy baked tacos with lime wedges, more cilantro, and the avocado lime crema drizzled on top.